The deployment of optical transmission and switching equipment in data networks has significantly increased data rates over earlier electrical technologies. Optical technology promises to provide an increasing data transmission and switching capability that will quickly exceed that of even the most ambitious electronic designs. Optical transmission and rates of 40 Gb/s, 100 Gb/s, and 160 Gb/s, will soon be implemented in the network core. Switching, however, is a non-deterministic process, subject to congestion, and therefore always requires adjacent queuing. No practical optical queuing mechanism is presently available, and it is clear that such capability, in a practical form, will not be available for many years. As a consequence, fast optical components will require equally fast and large electronic queuing, which will be impractical or impossible to design.
Over the last five years, approximately 85% of hardware-based router projects failed to deliver working equipment at data rates of 2.5 Gb/s and 10 Gb/s. The most significant difficulty faced in these designs was, and remains, complexity. Hardware based IP routers are simply too complex to allow one to be confident of a timely development cycle. Moreover, it is becoming increasingly clear that the network core, where data rates are highest, does not benefit from much in the complex feature set of IP routing; a simpler protocol such as multiprotocol label switching (MPLS) is entirely adequate. Along with greater simplicity, MPLS offers the ability to readily engineer traffic flows so as to avoid congestion and thereby improve network throughput. Indeed, MPLS based traffic engineering is currently deployed in many networks for this reason.